Piano sounding-board bridge



March 25, 1924.

C. S. WEBER PIANO SOUNDING BOARDBRIDGE Filed July 31. 1920 Patented Mar. 25, 1924.

UNITED STATES CHARLES S. WEBER, OF LOS ANGELES, CALIFORNIA.

PIANO SOUNDING-BOARD BRIDGE.

Application filed July 81, 1920. Serial No. 400,563.

I '0 all whom it may concern:

Be it known that I, CHARLES S. WEBER, citizen of the United States, residing at Los Angeles, in the county of Los Angeles and State of California, have invented certain new and useful Improvements in Piano Sounding-Board Bridges, of which the following is a specification.

This invention relates to bridges supported by the sound board. It has no bearing on wrest plate or hitch plate bridges.

Its object is to enrich the primary tone with sympathetic unisons derived from counter sections of the main string. Fig. 1 shows the improved bridge a, having two sides converging into a crest c. Fig. 2 is a top view of a portion of the bridge encompassing four notes of the three unisons each. Fig. 3 shows for the same portion of bridge the side farthest from the wrest pins. Fig. 4 shows the underside of the same portion. Fig. 5 shows two bridges on a secondary sound board secured at one end to a'central part of the main soundboard. Fig. 6 shows all the points in the extension at which sympathetic unisons may be obtained under condition of equal tension in both sections. Fig. 7 shows four strings in the extension set against two thicker ones in the main section. Fig. 8 on the left, shows the ortion'of same strings passin from the ass to the crest of a segment. 11 the right the underside of the same segment is shown.

Fig. 9 is a transverse section of the bridge showing the spreader t on the slope farthest from the wrest pins. Fig. 10 is a perspective view of the crest; F-i ures 10 and 1O are side and end views 0 other forms of the crest.

Although the upright piano is best suited for the changes demanded by this invention; the grand is chosen for the specification and drawings, as the horizontal position of the sounding board and of the strings in this form of pianos simplifies description and leads to a more concise wording of claims. I

As shown in Figs. 1, 2, 3, and 4, a string bent to form two parallel strands has both these passed from under the sound board through holes m and a leading above the base I: of the bridge a. The holes 917. being on the side of the bridge facing the hitch pins z, the holes n facing the wrest pins 72 As shown in Fig. 4 all three strings in the note A, as well as the lowest string in A1; have below the bridge one strand passed through m, the other strand through a, Whilst of the two upper strings in At? one has both strands passed through holes m, the other has both of them passed through holes 12. In either of the alternatives of stringing shown the strands anchored under the bridge to whatever part or device they may encounter between the holes they have passed through. As shown in Figures 1 and 2 all strands above the bridge emerging from holes we cross the crest 0 directed to wrest pins h, each strand forming a unison in the main section between 0 and the wrest bridge 7. Strands emerging from holes a cross the crest directed to hitch pins 2', and form unisons in the counter section between 0 and the hitch bridge g. This section is sounded by sympathetic action of the main strings that receive the primary impulse, as the blow of a piano hammer c in a grand, shown in Fig. 1. As the view taken in this figure puts both unisons of the main as well as of the counter section in a line, only the foremost strand is visible in either section, and appears to end abruptly under the reenforcing board Z both strands are, however, plainly shown in Figures 2, 3, and 4, where they form the two upper unisons of the note A#. It is evident that, when the four strands are drawn taut, either of the deflecting devices shown in Fig. 10, once in position will be held immovable in place even if otherwise unsecured. The stringing as shown may be objected to, for the reason that, in most ianos access to the rear of the sound board eing not only diffioult but in many cases practically impossible, re lacing a broken string would become at est a very laborious task. To meet this objection I secure below the bridge a set of auxiliary strings as shown in Figures 3 and 4 having parts p and 0, in Figures 3 and 4 to reach above the base of the bridge and offer a convenient anchorage to the musical strings. The preferred device shown in Figs. 3 and 4 resembles two links of a chain, the top link 0 consists of a number of strands of a thin wire, and is held in position by strands of a similar wire repeatedly passed down one hole and up again through the next, thereby to form the lower link p. As evident from the notes B and C in Figures 2, 3, and 4, the strands forming the main as well as the counter section, are by means of these links anchored under the bridge, in a way identical in principle to what was shown for the notes A and At, in the same figures. Evidently a number of fine strands spreading more or less, will out less into the reinforcing board Z than would a link formed of less strands. Still better result may be obtained where two lower links are drawn together by a central one as shown in Fig. i. Placing a resistant pad g under this, practically eliminates all danger oi the string cutting into the wood and slacking, especially if all corners be rounded between each two holes directly connected by auxiliary strings.

To prevent any two unisons sliding one too near the other I use the spreader, t, a slight elevation widening out towards the top on a slope of the bridge, as shown in Figs. 3 and 9. A simultaneous bearing of the string against the sides of the device as well as against the slope of the bridge results in additional improvement of tone.

It may be noted, however, that unless the pull of the strings be equal on both sides of the bridge, its support, the soundboard, averaging less than inch thickness, may give way, rendering the instrument useless. ll-Ieans for equalizing the said pull are shown and claimed in Patent No. 996,817 granted to me July 4th, 1911. Other means to obtain a similar result, will be shown.

Fig. 6 shows on a small scale five notes of the highest octave in a piano between 0* and 0 This being merely an explanation drawing, only one string for each note is shown. Besides the multiple lengths in the extensions the primary tone is also given that would result if the string were attached to a temporary bridge at any of the points showing lengths equal to that of the main string, and were sounded by direct impulse. Thus 0 attached at the lowest point would sound although, when influenced by sympathetic action alone of its main string, it will sound 0 no matter at which of the points marked it may be held.

As it only rarely happens that any of these marks should fall exactly in the hitch plate bridge, I make use of a principle so far not used in pianos, which allows spreading or contracting of the points at which unisons result in the extension. To this effeet I balance the pull of the main string with a thinner or thicker string in the extension. A thinner string pulling against a thicker one will have the greater tension. This demands a greater length for the former to sound in unison with the latter. As the extensions may safely be brought nearer the breaking point than is the case with the main strings where allowance for the blows of the hammer must be made, it was found that any string of the main section may safely be opposed by a string one or two sizes thinner. Making use of this means it was possible to tune the counter section of the highest octave in a way to have every string on the hitch plate touching a continuous bridge, shown in Fig. 6, yet to obtain a direct response for each note of the main section without perceptibly interfering with equality of pull on opposite sides of the sounding board bridge. Continued experiments resulted in a far reaching improvement. This consists in taking in the extension two or more thin strings it' required of different sizes to balance the one main string. There are 16 numbers of steel strings manufactured thinner than size 13, the thinnest now used for the primary strings of a piano. 1:") feet ot size 0000 are equal in weight to one foot of size 13. So many combinations are available that the improvement just described may be readily adapted to any note of the instrument wherever it should be desirable.

As this improvement allows the number of strings in the counter section being doubled, and as each string under proper conditions will add its sympathetic unison to the note of the corresponding main string, two strings in the main section opposed by 4: thinner ones in the counter section has been found preferable to having 3 strings in both sections of a note, the portion between crest and top link 0 of two strings d opposed by i strings e, is shown in Fig. 8, to the left. To have the four strings anchored by means of auxiliary strings 0 and 9 against an extended surface the holes 11. are made to diverge, as evident from the change in their position under the bridge; shown in the same figure to the left.

In tuning any string of the counter section, the corresponding pin is turned until the pitch marked near the pin is nearly reached, this being ascertained by sounding the string with a pick. In the next step only the corresponding main string is sounded by repeated strokes of the key, until by carefully turning the same pin as before, the sympathetic unisons become plainly audible. As this point is well marked and as any excess of turning will make the sympathetic efiect vanish, any tuner or musician may correctly tune this section without previous practice. To revent any string in the extension soun ing in unison with any except the correspond ing main string. I use the harmonic divisor, a device described in a patent granted to me April 19, 1887, Patent No. 361,384.

Having described my invention, what I claim is:

1. In apiano having a sounding board bridge. the combination of strings on each. side of said bridge, each string on one side extending over the crest of the bridge, and an elementbeneath the bridge connected to two such strings to hold them in position relative to said bridge, substantially as specified.

2. In a piano having a sounding board bridge, the combination of strings on each side of said bridge, one or more strings on one side of said bridge being associated with more than one string substantially opposite on the other side of said bridge, and means beneath said bridge for holding the strings in fixed relation thereto, substantially as specified. i

3. In a piano having a sounding board bridge, the combination of strings on each side of said bridge, one or more of the strin s on one side of said bridge being associated with a heavier string on the o posite side, and means beneath said bri ge for holding the strings in fixed relation thereto, substantially as set forth.

4. In a piano having a sounding board bridge, the combination of strings on each side of said bridge, strings on one side of said bridge being integrally connected in pairs and a spreader on said brid e on the side opposite the active part of sai pair of strings to maintain the two strings of said pair separate, substantially as described.

5. A soundin board bridge for a piano comprising a ase having holes therein adapted to receive anchoring members for the strings and a crest adapted to support strings received from either side, and sides sloping away from said crest to support said strings, substantially as shown.

6. A piano having strings on both sides of the sounding board bridge, the strings on one side of said bridge passing over the crest of said bridge to a point on the opposite side thereof and means anchored below said bridge and connected to said strings to retain said strings in place, substantially as s ecified.

In testimony w ereof, I have signed my.

name.

CHARLES S. WEBER. 

